Answer:
a. lead users
Step-by-step explanation:
Lead users -
The term lead users was coined by Eric von Hippel .
And it is defined as , the user of a product or commodity or service , which is still not publicly available and these users innovate or modify according to their convenience .
Same is the case with data given in the question , the customers are the Lead users , who give new innovative ideas to improve or modify the product .